This project seeks to determine whether the regulation of lens fiber differentiation and maturation is associated with alterations in the plasma membrane. The principal lipid and protein components of embryonic and adult chicken lenses have been identified and their metabolism is being investigated. The relationships between phospholipid metabolism and differentiation have been studied in vivo and in vitro using isotopic labeling techniques and computer modeling. A transient increase in the transmethylation of phospatidylethanolamine has been shown to be an initial event in lens fiber cell formation. In addition, rapid turnover of phosphatidylinositol, which occurs in lens epithelial cells, ceases abruptly following the initiation of lens fiber formation both in vivo and in vitro.